The Merlin Pool by Monte Merrick

Tom Jessup is touring the national parks with his dog, Buster. When they’re at Yellowstone, a member of a tour group is shoved from behind into one of the deadly volcanic pools. Tom doesn’t want to get involved in the murder. He’s retired, he’s on vacation, and has had enough drama in his life. But curiosity gets the better of him. The tour members, all suspects, find his friendly nature and willing ear irresistible. Pretty soon Tom is up to his neck in clues and secrets. A second murder happens, then a third. Unless he finds the killer Tom - or his beloved dog – could be the next victim.